I've tried both systems extensively and expensively and now gone back to indexed downtube shifters on my derailleur bikes
Sti: bad: complex, expensive, fiddly to fit, limited life, sometimes mis shift and difficult to use with cold/wet/tired hands, sometimes shift instead of braking and vice versa, fiddly front trimming (based on Ultegra 6600 2x10 compact AND 6700 3x10 full systems)
good: can shift whilst standing on pedals.
Bar ends : bad: about half a kilo heavier than downtube shifter set up ( I weighed it.), can attack knees, still not an optimal ergonomic shifter position. (Based on 8 and 9 speed Ultegra index/friction bar ends)
good: reliable, long lived, multiple shifts easy, trimming easy. Emergency downshift really easy with low normal derailleur.
Downtube set up by contrast is simplest, lightest, tidiest, easiest to set up, cheapest, least integrated, most reliable, most flexible for hybridised transmissions, and for me at least; as ergonomic as bar ends. I find bigger arm/hand/shoulder and back movements beneficial as they help reduce RSI stress by requiring more mobility. Downside may be more planning required for shifting but as I'm not racing this is actually a pleasure, and I no longer need to shift standing up as a hybridised transmission allows me to have low enough gears for climbing seated.
Mind you some of the centrally mounted systems above could be good but the boutique parts are generally so expensive
The cocktail of Zen simplicity and Luddism is the one for me.
Try them all it's often suprising and counter intuitive what works best.
Ian
